An electronic paper display permits rolling of an electronic information display medium itself like paper, and permits electronic printing and erasing, and it is a display capable of maintaining an electronic printing display without needing electric power.
As such an electronic paper display, for example, displays employing the principles of a particle movement type, a phase change type, a heat sensitive dyestuff type, and a liquid crystal type have been proposed.
However, these types have a complicated device structure and become expensive, and have difficulty in processing into a thin medium. Furthermore, coloring is also difficult.
The present inventors have disclosed an electrochromic element using an organic-metallic hybrid polymer in which a plurality of bis(terpyridine)s are linked to each other via metallic ions of Fe, Co, and Ru et al. (Patent Literature 3), and have proposed applying of the electronic paper display (see, Patent Literatures 1 to 10). Recently, the present inventors have developed an electronic printed medium in which the organic-metallic hybrid polymer has been printed onto a PET film.
However, the electrochromic element has a structure in which an organic-metallic hybrid polymer layer and a gel electrolyte layer are laminated and the laminated product is sandwiched by electrode layers from the both sides (see FIG. 3 of Patent Literature 3), and has a problem that the presence of the electrode layer causes poor flexibility.
Similarly, the electronic printed medium also has a problem that it has a structure obtained by removing a gel electrolyte layer and an electrode layer at a gel electrolyte layer side from the electrochromic element structure, so that it has poor flexibility due to the presence of the electrode layer.